Routing Data Over Wireless Communication Links

ABSTRACT

Certain examples accommodate data routing optimizations. An example method comprises receiving, by a first playback device, data to be directed to at least a second playback device, the data comprising: i) audio data and ii) non-audio data. The method comprises transmitting, by the first playback device, the non-audio data to the second playback device via a third playback device according to a network protocol for communication between the first playback device and at least the second playback device via a wireless communication link. The method further comprises determining, by the first playback device, that a signal strength of the wireless communication link is above a threshold, and in response to the determination, transmitting the audio data to the second playback device via the wireless communication link, wherein transmitting the audio data comprises transmitting the audio data over the wireless communication link not according to the network protocol.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of, and claims the benefit ofpriority to U.S. patent application Ser. No. 15/613,603 titled “RoutingData Over Wireless Communication Links,” filed on Jun. 5, 2017, whichclaims priority to and is a continuation of U.S. patent application Ser.No. 14/852,282 titled “Data Routing Optimization,” filed on Sep. 11,2015, which claims priority to and is a continuation of U.S. patentapplication Ser. No. 13/648,486, entitled “Method and Apparatus forMulticast Optimization” filed on Oct. 10, 2012, each of which are herebyincorporated by reference in their entirety for all purposes.

FIELD OF THE DISCLOSURE

The disclosure is related to consumer goods and, more particularly, tosystems, products, features, services, and other items directed to mediaplayback or some aspect thereof.

BACKGROUND

Technological advancements have increased the accessibility of musiccontent, as well as other types of media, such as television content,movies, and interactive content. For example, a user can access audio,video, or both audio and video content over the Internet through anonline store, an Internet radio station, a music service, a movieservice, and so on, in addition to the more traditional avenues ofaccessing audio and video content. Demand for audio, video, and bothaudio and video content inside and outside of the home continues toincrease.

BRIEF DESCRIPTION OF THE DRAWINGS

Features, aspects, and advantages of the presently disclosed technologyare better understood with regard to the following description, appendedclaims, and accompanying drawings where:

FIG. 1 shows an example configuration in which certain embodiments maybe practiced;

FIG. 2A shows an illustration of an example zone player having abuilt-in amplifier and speakers;

FIG. 2B shows an illustration of an example zone player having abuilt-in amplifier and connected to external speakers;

FIG. 2C shows an illustration of an example zone player connected to anA/V receiver and speakers;

FIG. 3 shows an illustration of an example controller;

FIG. 4 shows an internal functional block diagram of an example zoneplayer;

FIG. 5 shows an internal functional block diagram of an examplecontroller;

FIG. 6 shows an example ad-hoc playback network;

FIG. 7 shows a system including a plurality of networks including acloud-based network and at least one local playback network;

FIG. 8 shows an internal functional block diagram of an example zoneplayer supporting direct routing;

FIG. 9 shows an example network configuration;

FIG. 10 shows an internal functional block diagram of the example directrouting enabler of FIG. 8;

FIGS. 11 and 12 show flowcharts for example methods or processes for theexample direct communication enabler of FIGS. 8 and/or 10;

FIG. 13 illustrates an example network providing multicast frameforwarding; and

FIG. 14 shows a flowchart for an example method or process to enabledirect routing optimization to forward multicast traffic in a network.

In addition, the drawings are for the purpose of illustrating exampleembodiments, but it is understood that the inventions are not limited tothe arrangements and instrumentality shown in the drawings.

DETAILED DESCRIPTION I. Overview

The present disclosure provides various mechanisms that optimizemulticast data routing in an audio network. In an embodiment, the audionetwork uses a wireless (or wired, or both wireless and wired) meshnetwork that allows devices, such as zone players, and access points tocommunicate with each other. Additionally, the network system generallyuses a network protocol like a Spanning Tree Protocol (STP) to providecertain benefits, such as to prevent routing loops, but is optimized foran audio system. In an embodiment, a networked audio component, such asa zone player, can override the use of the STP protocol in view of adirect routing scheme, described herein, to optimize certain kinds ofmulticast traffic.

Particularly, to prevent a routing loop, the STP or similar networkprotocols, restrict data transmission capabilities of some devices on anetwork. For example, a first zone player (e.g., represented as a nodein an audio network) of an STP network may be blocked, per the protocol,from sending data directly to a second zone player of the STP network.In other words, the first zone player is required to send data destinedfor the second zone player through an intermediary device, such as athird zone player (e.g., a root node).

Devices of a network that are restricted by a governing protocol, likeSTP, from transmitting data directly with certain other devices of thenetwork are referred to herein as “blocked.” That is, when the networkprotocol prohibits the first device of the network from directly routingdata to the second device, the direct routing (or direct link) betweenthe first and second devices is said to be blocked by the governingnetwork protocol.

Example methods, apparatus, systems, and articles of manufacturedisclosed herein provide devices, such as a zone player, with an abilityto directly route data, such as audio data, to neighboring devicesdespite the protocol designation of the link as “blocked.” As describedin greater detail below, example methods, apparatus, systems, andarticles of manufacture disclosed herein create a direct routing pathbetween a first device and a second device where the first device isotherwise blocked (e.g., according to a designation of the governingprotocol) from routing data to the second device.

The direct routing scheme provided by the example methods, apparatus,systems, and articles of manufacture disclosed herein enables the firstdevice to bypass the indirect forwarding route established by thegoverning protocol, thereby transmitting the forwarded information to adestination device faster and with less network congestion. In anembodiment, the direct route provided by the example methods, apparatus,systems, and articles of manufacture disclosed herein is used inconnection with forwarding data (e.g., frames) of a certain type offrame, such as frames having a threshold quality of service (QoS)characteristic(s). In another embodiment, the direct routing scheme isused for data carrying audio content when possible, whereas thegoverning protocol is followed for other types of data. In yet anotherembodiment, the direct routing scheme is used by devices on the audionetwork, such as zone players, to forward multicast traffic using aunicast transmission methodology when possible.

In some examples disclosed herein, one or more characteristicsindicative of the connection quality between the first and seconddevices is monitored. For example, a wireless signal-to-noise level(SNR), also referred to herein as signal strength indicator (SSI),between the first and second devices is monitored to determine a healthand/or a measure of reliability of the direct link between the first andsecond devices. Direct routing may be used, or considered, when thehealth of the connection meets a certain threshold.

If the monitored characteristic(s) indicate a weakness of theconnection, the direct routing between the otherwise blocked devices isdisabled. As a result, the first device communicates with the seconddevice in accordance with the governing protocol's “blocked” designationuntil the monitored characteristic(s) indicate that the connectionbetween the first and second devices has returned to a healthy, reliablestate.

Although the following discloses example systems, methods, apparatus,and articles of manufacture including, among other components, firmwareand/or software executed on hardware, it should be noted that suchsystems, methods, apparatus, and/or articles of manufacture are merelyillustrative and should not be considered as limiting. For example, itis contemplated that any or all of these firmware, hardware, and/orsoftware components could be embodied exclusively in hardware,exclusively in software, exclusively in firmware, or in any combinationof hardware, software, and/or firmware. Accordingly, while the followingdescribes example systems, methods, apparatus, and/or articles ofmanufacture, the examples provided are not the only way(s) to implementsuch systems, methods, apparatus, and/or articles of manufacture.

When any of the appended claims are read to cover a purely softwareand/or firmware implementation, at least one of the elements in at leastone example is hereby expressly defined to include a tangible mediumsuch as a memory, DVD, CD, Blu-ray, and so on, storing the softwareand/or firmware.

Reference herein to “embodiment” means that a particular feature,structure, or characteristic described in connection with the embodimentcan be included in at least one example embodiment of the invention. Theappearances of this phrase in various places in the specification arenot necessarily all referring to the same embodiment, nor are separateor alternative embodiments mutually exclusive of other embodiments. Assuch, the embodiments described herein, explicitly and implicitlyunderstood by one skilled in the art, can be combined with otherembodiments.

These embodiments and many additional embodiments are described morebelow. Further, the detailed description is presented largely in termsof illustrative environments, systems, procedures, steps, logic blocks,processing, and other symbolic representations that directly orindirectly resemble the operations of data processing devices coupled tonetworks. These process descriptions and representations are typicallyused by those skilled in the art to most effectively convey thesubstance of their work to others skilled in the art. Numerous specificdetails are set forth to provide a thorough understanding of the presentdisclosure. However, it is understood to those skilled in the art thatcertain embodiments of the present disclosure can be practiced withoutcertain, specific details. In other instances, well known methods,procedures, components, and circuitry have not been described in detailto avoid unnecessarily obscuring aspects of the embodiments.

II. An Example Operating Environment

Referring now to the drawings, in which like numerals can refer to likeparts throughout the figures, FIG. 1 shows an example systemconfiguration 100 in which one or more embodiments disclosed herein canbe practiced or implemented.

By way of illustration, the system configuration 100 represents a homewith multiple zones, though the home could have been configured withonly one zone. Each zone, for example, may represent a different room orspace, such as an office, bathroom, bedroom, kitchen, dining room,family room, home theater room, utility or laundry room, and patio. Asingle zone might also include multiple rooms or spaces if soconfigured. One or more of zone players 102-124 are shown in eachrespective zone. A zone player 102-124, also referred to as a playbackdevice, multimedia unit, speaker, player, and so on, provides audio,video, and/or audiovisual output. A controller 130 (e.g., shown in thekitchen for purposes of illustration) provides control to the systemconfiguration 100. Controller 130 may be fixed to a zone, oralternatively, mobile such that it can be moved about the zones. Systemconfiguration 100 may also include more than one controller 130. Thesystem configuration 100 illustrates an example whole house audiosystem, though it is understood that the technology described herein isnot limited to its particular place of application or to an expansivesystem like a whole house audio system 100 of FIG. 1.

a. Example Zone Players

FIGS. 2A, 2B, and 2C show example types of zone players. Zone players200, 202, and 204 of FIGS. 2A, 2B, and 2C, respectively, can correspondto any of the zone players 102-124 of FIG. 1, for example. In someembodiments, audio is reproduced using only a single zone player, suchas by a full-range player. In some embodiments, audio is reproducedusing two or more zone players, such as by using a combination offull-range players or a combination of full-range and specializedplayers. In some embodiments, zone players 200-204 may also be referredto as a “smart speaker,” because they contain processing capabilitiesbeyond the reproduction of audio, more of which is described below.

FIG. 2A illustrates zone player 200 that includes sound producingequipment 208 capable of reproducing full-range sound. The sound maycome from an audio signal that is received and processed by zone player200 over a wired or wireless data network. Sound producing equipment 208includes one or more built-in amplifiers and one or more speakers. Abuilt-in amplifier is described more below with respect to FIG. 4. Aspeaker or acoustic transducer can include, for example, any of atweeter, a mid-range driver, a low-range driver, and a subwoofer. Insome embodiments, zone player 200 can be statically or dynamicallyconfigured to play stereophonic audio, monaural audio, or both. In someembodiments, zone player 200 is configured to reproduce a subset offull-range sound, such as when zone player 200 is grouped with otherzone players to play stereophonic audio, monaural audio, and/or surroundaudio or when the audio content received by zone player 200 is less thanfull-range.

FIG. 2B illustrates zone player 202 that includes a built-in amplifierto power a set of detached speakers 210. A detached speaker can include,for example, any type of loudspeaker. Zone player 202 may be configuredto power one, two, or more separate loudspeakers. Zone player 202 may beconfigured to communicate an audio signal (e.g., right and left channelaudio or more channels depending on its configuration) to the detachedspeakers 210 via a wired path.

FIG. 2C illustrates zone player 204 that does not include a built-inamplifier, but is configured to communicate an audio signal, receivedover a data network, to an audio (or “audio/video”) receiver 214 withbuilt-in amplification.

Referring back to FIG. 1, in some embodiments, one, some, or all of thezone players 102 to 124 can retrieve audio directly from a source. Forexample, a zone player may contain a playlist or queue of audio items tobe played (also referred to herein as a “playback queue”). Each item inthe queue may comprise a uniform resource identifier (URI) or some otheridentifier. The URI or identifier can point the zone player to the audiosource. The source might be found on the Internet (e.g., the cloud),locally from another device over data network 128 (described furtherbelow), from the controller 130, stored on the zone player itself, orfrom an audio source communicating directly to the zone player. In someembodiments, the zone player can reproduce the audio itself, send it toanother zone player for reproduction, or both where the audio is playedby the zone player and one or more additional zone players in synchrony.In some embodiments, the zone player can play a first audio content (ornot play at all), while sending a second, different audio content toanother zone player(s) for reproduction.

By way of illustration, SONOS, Inc. of Santa Barbara, Calif. presentlyoffers for sale zone players referred to as a “PLAY:5,” “PLAY:3,”“CONNECT:AMP,” “CONNECT,” and “SUB.” Any other past, present, and/orfuture zone players can additionally or alternatively be used toimplement the zone players of example embodiments disclosed herein.Additionally, it is understood that a zone player is not limited to theparticular examples illustrated in FIGS. 2A, 2B, and 2C or to the SONOSproduct offerings. For example, a zone player may include a wired orwireless headphone. In yet another example, a zone player might includea sound bar for television. In yet another example, a zone player caninclude or interact with a docking station for an Apple IPOD™ or similardevice.

b. Example Controllers

FIG. 3 illustrates an example wireless controller 300 in docking station302. By way of illustration, controller 300 can correspond tocontrolling device 130 of FIG. 1. Docking station 302, if provided, maybe used to charge a battery of controller 300. In some embodiments,controller 300 is provided with a touch screen 304 that allows a user tointeract through touch with the controller 300, for example, to retrieveand navigate a playlist of audio items, control operations of one ormore zone players, and provide overall control of the systemconfiguration 100. In certain embodiments, any number of controllers canbe used to control the system configuration 100. In some embodiments,there can be a limit set on the number of controllers that can controlthe system configuration 100. The controllers might be wireless likewireless controller 300 or wired to data network 128.

In some embodiments, if more than one controller is used in system 100,then each controller may be coordinated to display common content, andmay all be dynamically updated to indicate changes made from a singlecontroller. Coordination can occur, for instance, by a controllerperiodically requesting a state variable directly or indirectly from oneor more zone players; the state variable may provide information aboutsystem 100, such as current zone group configuration, what is playing inone or more zones, volume levels, and other items of interest. The statevariable may be passed around on data network 128 between zone players(and controllers, if so desired) as needed or as often as programmed.

In addition, an application running on any network-enabled portabledevice, such as an IPHONE®, IPAD®, ANDROID™ powered phone, or any othersmart phone or network-enabled device can be used as controller 130. Anapplication running on a laptop or desktop personal computer (PC) orMAC™ can also be used as controller 130. Such controllers may connect tosystem 100 through an interface with data network 128, a zone player, awireless router, or using some other configured connection path. Examplecontrollers offered by Sonos, Inc. of Santa Barbara, Calif. include a“Controller 200,” “SONOS® CONTROL,” “SONOS® Controller for IPHONE®,”“SONOS® Controller for IPAD™” “SONOS® Controller for ANDROID™,” “SONOS®Controller for MAC™ or PC.”

c. Example Data Connection

Zone players 102 to 124 of FIG. 1 are coupled directly or indirectly toa data network, such as data network 128. Controller 130 may also becoupled directly or indirectly to data network 128 or individual zoneplayers. Data network 128 is represented by an octagon in the figure tostand out from other representative components. While data network 128is shown in a single location, it is understood that such a network isdistributed in and around system 100. Particularly, data network 128 canbe a wired network, a wireless network, or a combination of both wiredand wireless networks. In some embodiments, one or more of the zoneplayers 102-124 are wirelessly coupled to data network 128 based on aproprietary mesh network. In some embodiments, one or more of the zoneplayers 102-124 are wirelessly coupled to data network 128 using anon-mesh topology. In some embodiments, one or more of the zone players102-124 are coupled via a wire to data network 128 using Ethernet orsimilar technology. In addition to the one or more zone players 102-124connecting to data network 128, data network 128 can further allowaccess to a wide area network, such as the Internet.

In some embodiments, connecting any of the zone players 102-124, or someother connecting device, to a broadband router, can create data network128. Other zone players 102-124 can then be added wired or wirelessly tothe data network 128. For example, a zone player (e.g., any of zoneplayers 102-124) can be added to the system configuration 100 by simplypressing a button on the zone player itself (or perform some otheraction), which enables a connection to be made to data network 128. Thebroadband router can be connected to an Internet Service Provider (ISP),for example. The broadband router can be used to form another datanetwork within the system configuration 100, which can be used in otherapplications (e.g., web surfing). Data network 128 can also be used inother applications, if so programmed. An example, second network mayimplement SONOSNET™ protocol, developed by SONOS, Inc. of Santa Barbara.SONOSNET™ represents a secure, AES-encrypted, peer-to-peer wireless meshnetwork. Alternatively, in certain embodiments, the data network 128 isthe same network, such as a traditional wired or wireless network, usedfor other applications in the household.

d. Example Zone Configurations

A particular zone can contain one or more zone players. For example, thefamily room of FIG. 1 contains two zone players 106 and 108, while thekitchen is shown with one zone player 102. In another example, the hometheater room contains additional zone players to play audio from a 5.1channel or greater audio source (e.g., a movie encoded with 5.1 orgreater audio channels). In some embodiments, one can position a zoneplayer in a room or space and assign the zone player to a new orexisting zone via controller 130. As such, zones may be created,combined with another zone, removed, and given a specific name (e.g.,“Kitchen”), if so desired and programmed to do so with controller 130.Moreover, in some embodiments, zone configurations may be dynamicallychanged even after being configured using controller 130 or some othermechanism.

In some embodiments, if a zone contains two or more zone players, suchas the two zone players 106 and 108 in the family room, then the twozone players 106 and 108 can be configured to play the same audio sourcein synchrony, or the two zone players 106 and 108 can be paired to playtwo separate sounds in left and right channels, for example. In otherwords, the stereo effects of a sound can be reproduced or enhancedthrough the two zone players 106 and 108, one for the left sound and theother for the right sound. In certain embodiments, paired zone players(also referred to as “bonded zone players”) can play audio in synchronywith other zone players in the same or different zones.

In some embodiments, two or more zone players can be sonicallyconsolidated to form a single, consolidated zone player. A consolidatedzone player (though made up of multiple, separate devices) can beconfigured to process and reproduce sound differently than anunconsolidated zone player or zone players that are paired, because aconsolidated zone player will have additional speaker drivers from whichsound can be passed. The consolidated zone player can further be pairedwith a single zone player or yet another consolidated zone player. Eachplayback device of a consolidated playback device can be set in aconsolidated mode, for example.

According to some embodiments, one can continue to do any of: group,consolidate, and pair zone players, for example, until a desiredconfiguration is complete. The actions of grouping, consolidation, andpairing are preferably performed through a control interface, such asusing controller 130, and not by physically connecting and re-connectingspeaker wire, for example, to individual, discrete speakers to createdifferent configurations. As such, certain embodiments described hereinprovide a more flexible and dynamic platform through which soundreproduction can be offered to the end-user.

e. Example Audio Sources

In some embodiments, each zone can play from the same audio source asanother zone or each zone can play from a different audio source. Forexample, someone can be grilling on the patio and listening to jazzmusic via zone player 124, while someone is preparing food in thekitchen and listening to classical music via zone player 102. Further,someone can be in the office listening to the same jazz music via zoneplayer 110 that is playing on the patio via zone player 124. In someembodiments, the jazz music played via zone players 110 and 124 isplayed in synchrony. Synchronizing playback amongst zones allows forsomeone to pass through zones while seamlessly (or substantiallyseamlessly) listening to the audio. Further, zones can be put into a“party mode” such that all associated zones will play audio insynchrony.

Sources of audio content to be played by zone players 102-124 arenumerous. In some embodiments, music on a zone player itself may beaccessed and a played. In some embodiments, music from a personallibrary stored on a computer or networked-attached storage (NAS) may beaccessed via the data network 128 and played. In some embodiments,Internet radio stations, shows, and podcasts can be accessed via thedata network 128. Music or cloud services that let a user stream and/ordownload music and audio content can be accessed via the data network128. Further, music can be obtained from traditional sources, such as aturntable or CD player, via a line-in connection to a zone player, forexample. Audio content can also be accessed using a different protocol,such as AIRPLAY™, which is a wireless technology by Apple, Inc., forexample. Audio content received from one or more sources can be sharedamongst the zone players 102 to 124 via data network 128 and/orcontroller 130. The above-disclosed sources of audio content arereferred to herein as network-based audio information sources. However,network-based audio information sources are not limited thereto.

In some embodiments, the example home theater zone players 116, 118, 120are coupled to an audio information source such as a television 132. Insome examples, the television 132 is used as a source of audio for thehome theater zone players 116, 118, 120, while in other examples audioinformation from the television 132 can be shared with any of the zoneplayers 102-124 in the audio system 100.

III. Example Zone Players

Referring now to FIG. 4, there is shown an example block diagram of azone player 400 in accordance with an embodiment. Zone player 400includes a network interface 402, a processor 408, a memory 410, anaudio processing component 412, one or more modules 414, an audioamplifier 416, and a speaker unit 418 coupled to the audio amplifier416. FIG. 2A shows an example illustration of such a zone player. Othertypes of zone players may not include the speaker unit 418 (e.g., suchas shown in FIG. 2B) or the audio amplifier 416 (e.g., such as shown inFIG. 2C). Further, it is contemplated that the zone player 400 can beintegrated into another component. For example, the zone player 400could be constructed as part of a television, lighting, or some otherdevice for indoor or outdoor use.

In some embodiments, network interface 402 facilitates a data flowbetween zone player 400 and other devices on a data network 128. In someembodiments, in addition to getting audio from another zone player ordevice on data network 128, zone player 400 may access audio directlyfrom the audio source, such as over a wide area network or on the localnetwork. In some embodiments, the network interface 402 can furtherhandle the address part of each packet so that it gets to the rightdestination or intercepts packets destined for the zone player 400.Accordingly, in certain embodiments, each of the packets includes anInternet Protocol (IP)-based source address as well as an IP-baseddestination address.

In some embodiments, network interface 402 can include one or both of awireless interface 404 and a wired interface 406. The wireless interface404, also referred to as a radio frequency (RF) interface, providesnetwork interface functions for the zone player 400 to wirelesslycommunicate with other devices (e.g., other zone player(s), speaker(s),receiver(s), component(s) associated with the data network 128, and soon) in accordance with a communication protocol (e.g., any wirelessstandard including IEEE 802.11a, 802.11b, 802.11g, 802.11n, or 802.15).Wireless interface 404 may include one or more radios. To receivewireless signals and to provide the wireless signals to the wirelessinterface 404 and to transmit wireless signals, the zone player 400includes one or more antennas 420. The wired interface 406 providesnetwork interface functions for the zone player 400 to communicate overa wire with other devices in accordance with a communication protocol(e.g., IEEE 802.3). In some embodiments, a zone player includes multiplewireless 404 interfaces. In some embodiments, a zone player includesmultiple wired 406 interfaces. In some embodiments, a zone playerincludes both of the interfaces 404 and 406. In some embodiments, a zoneplayer 400 includes only the wireless interface 404 or the wiredinterface 406.

In some embodiments, the processor 408 is a clock-driven electronicdevice that is configured to process input data according toinstructions stored in memory 410. The memory 410 is data storage thatcan be loaded with one or more software module(s) 414, which can beexecuted by the processor 408 to achieve certain tasks. In theillustrated embodiment, the memory 410 is a tangible machine-readablemedium storing instructions that can be executed by the processor 408.In some embodiments, a task might be for the zone player 400 to retrieveaudio data from another zone player or a device on a network (e.g.,using a uniform resource locator (URL) or some other identifier). Insome embodiments, a task may be for the zone player 400 to send audiodata to another zone player or device on a network. In some embodiments,a task may be for the zone player 400 to synchronize playback of audiowith one or more additional zone players. In some embodiments, a taskmay be to pair the zone player 400 with one or more zone players tocreate a multi-channel audio environment. Additional or alternativetasks can be achieved via the one or more software module(s) 414 and theprocessor 408.

The audio processing component 412 can include one or moredigital-to-analog converters (DAC), an audio preprocessing component, anaudio enhancement component or a digital signal processor, and so on. Insome embodiments, the audio processing component 412 may be part ofprocessor 408. In some embodiments, the audio that is retrieved via thenetwork interface 402 is processed and/or intentionally altered by theaudio processing component 412. Further, the audio processing component412 can produce analog audio signals. The processed analog audio signalsare then provided to the audio amplifier 416 for play back throughspeakers 418. In addition, the audio processing component 412 caninclude circuitry to process analog or digital signals as inputs to playfrom zone player 400, send to another zone player on a network, or bothplay and send to another zone player on the network. An example inputincludes a line-in connection (e.g., an auto-detecting 3.5 mm audioline-in connection).

The audio amplifier 416 is a device(s) that amplifies audio signals to alevel for driving one or more speakers 418. The one or more speakers 418can include an individual transducer (e.g., a “driver”) or a completespeaker system that includes an enclosure including one or more drivers.A particular driver can be a subwoofer (e.g., for low frequencies), amid-range driver (e.g., for middle frequencies), and a tweeter (e.g.,for high frequencies), for example. An enclosure can be sealed orported, for example. Each transducer may be driven by its own individualamplifier.

A commercial example, presently known as the PLAY:5, is a zone playerwith a built-in amplifier and speakers that is capable of retrievingaudio directly from the source, such as on the Internet or on the localnetwork, for example. In particular, the PLAY:5 is a five-amp,five-driver speaker system that includes two tweeters, two mid-rangedrivers, and one woofer. When playing audio content via the PLAY:5, theleft audio data of a track is sent out of the left tweeter and leftmid-range driver, the right audio data of a track is sent out of theright tweeter and the right mid-range driver, and mono bass is sent outof the subwoofer. Further, both mid-range drivers and both tweeters havethe same equalization (or substantially the same equalization). That is,they are both sent the same frequencies but from different channels ofaudio. Audio from Internet radio stations, online music and videoservices, downloaded music, analog audio inputs, television, DVD, and soon, can be played from the PLAY:5.

IV. Example Controller

Referring now to FIG. 5, there is shown an example block diagram forcontroller 500, which can correspond to the controlling device 130 inFIG. 1. Controller 500 can be used to facilitate the control ofmulti-media applications, automation and others in a system. Inparticular, the controller 500 may be configured to facilitate aselection of a plurality of audio sources available on the network andenable control of one or more zone players (e.g., the zone players102-124 in FIG. 1) through a wireless or wired network interface 508.According to one embodiment, the wireless communications is based on anindustry standard (e.g., infrared, radio, wireless standards includingIEEE 802.11a, 802.11b, 802.11g, 802.11n, 802.15, and so on). Further,when a particular audio is being accessed via the controller 500 orbeing played via a zone player, a picture (e.g., album art) or any otherdata, associated with the audio and/or audio source can be transmittedfrom a zone player or other electronic device to controller 500 fordisplay.

Controller 500 is provided with a screen 502 and an input interface 514that allows a user to interact with the controller 500, for example, tonavigate a playlist of many multimedia items and to control operationsof one or more zone players. The screen 502 on the controller 500 can bean LCD screen, for example. The screen 500 communicates with and iscommanded by a screen driver 504 that is controlled by a microcontroller(e.g., a processor) 506. The memory 510 can be loaded with one or moreapplication modules 512 that can be executed by the microcontroller 506with or without a user input via the user interface 514 to achievecertain tasks. In some embodiments, an application module 512 isconfigured to facilitate grouping a number of selected zone players intoa zone group and synchronizing the zone players for audio play back. Insome embodiments, an application module 512 is configured to control theaudio sounds (e.g., volume) of the zone players in a zone group. Inoperation, when the microcontroller 506 executes one or more of theapplication modules 512, the screen driver 504 generates control signalsto drive the screen 502 to display an application specific userinterface accordingly.

The controller 500 includes a network interface 508 that facilitateswired or wireless communication with a zone player. In some embodiments,the commands such as volume control and audio playback synchronizationare sent via the network interface 508. In some embodiments, a savedzone group configuration is transmitted between a zone player and acontroller via the network interface 508. The controller 500 can controlone or more zone players, such as 102-124 of FIG. 1. There can be morethan one controller for a particular system, and each controller mayshare common information with another controller, or retrieve the commoninformation from a zone player, if such a zone player storesconfiguration data (e.g., such as a state variable). Further, acontroller can be integrated into a zone player.

It should be noted that other network-enabled devices such as anIPHONE®, IPAD® or any other smart phone or network-enabled device (e.g.,a networked computer such as a PC or MAC®) can also be used as acontroller to interact or control zone players in a particularenvironment. In some embodiments, a software application or upgrade canbe downloaded onto a network-enabled device to perform the functionsdescribed herein.

In certain embodiments, a user can create a zone group (also referred toas a bonded zone) including at least two zone players from thecontroller 500. The zone players in the zone group can play audio in asynchronized fashion, such that all of the zone players in the zonegroup play back an identical audio source or a list of identical audiosources in a synchronized manner such that no (or substantially no)audible delays or hiccups are to be heard. Similarly, in someembodiments, when a user increases the audio volume of the group fromthe controller 500, the signals or data of increasing the audio volumefor the group are sent to one of the zone players and causes other zoneplayers in the group to be increased together in volume.

A user via the controller 500 can group zone players into a zone groupby activating a “Link Zones” or “Add Zone” soft button, or de-grouping azone group by activating an “Unlink Zones” or “Drop Zone” button. Forexample, one mechanism for ‘joining’ zone players together for audioplay back is to link a number of zone players together to form a group.To link a number of zone players together, a user can manually link eachzone player or room one after the other. For example, assume that thereis a multi-zone system that includes the following zones: Bathroom,Bedroom, Den, Dining Room, Family Room, and Foyer.

In certain embodiments, a user can link any number of the six zoneplayers, for example, by starting with a single zone and then manuallylinking each zone to that zone.

In certain embodiments, a set of zones can be dynamically linkedtogether using a command to create a zone scene or theme (subsequent tofirst creating the zone scene). For instance, a “Morning” zone scenecommand can link the Bedroom, Office, and Kitchen zones together in oneaction. Without this single command, the user would manually andindividually link each zone. The single command may include a mouseclick, a double mouse click, a button press, a gesture, or some otherprogrammed action. Other kinds of zone scenes can be programmed.

In certain embodiments, a zone scene can be triggered based on time(e.g., an alarm clock function). For instance, a zone scene can be setto apply at 8:00 am. The system can link appropriate zonesautomatically, set specific music to play, and then stop the music aftera defined duration. Although any particular zone can be triggered to an“On” or “Off” state based on time, for example, a zone scene enables anyzone(s) linked to the scene to play a predefined audio (e.g., afavorable song, a predefined playlist) at a specific time and/or for aspecific duration. If, for any reason, the scheduled music failed to beplayed (e.g., an empty playlist, no connection to a share, failedUniversal Plug and Play (UPnP), no Internet connection for an InternetRadio station, and so on), a backup buzzer can be programmed to sound.The buzzer can include a sound file that is stored in a zone player, forexample.

V. Example Ad-Hoc Network

Certain particular examples are now provided in connection with FIG. 6to describe, for purposes of illustration, certain systems and methodsto provide and facilitate connection to a playback network. FIG. 6 showsthat there are three zone players 602, 604 and 606 and a controller 608that form a network branch that is also referred to as an Ad-Hoc network610. The network 610 may be wireless, wired, or a combination of wiredand wireless. In general, an Ad-Hoc (or “spontaneous”) network is alocal area network or other small network in which there is generally noone access point for all traffic. With an established Ad-Hoc network610, the devices 602, 604, 606 and 608 can all communicate with eachother in a “peer-to-peer” style of communication, for example.Furthermore, devices may come/and go from the network 610, and thenetwork 610 will automatically reconfigure itself without needing theuser to reconfigure the network 610. While an Ad-Hoc network isreferenced in FIG. 6, it is understood that a playback network may bebased on a type of network that is completely or partially differentfrom an Ad-Hoc network.

Using the Ad-Hoc network 610, the devices 602, 604, 606, and 608 canshare or exchange one or more audio sources and be dynamically groupedto play the same or different audio sources. For example, the devices602 and 604 are grouped to playback one piece of music, and at the sametime, the device 606 plays back another piece of music. In other words,the devices 602, 604, 606 and 608, as shown in FIG. 6, form a HOUSEHOLDthat distributes audio and/or reproduces sound. As used herein, the termHOUSEHOLD (provided in uppercase letters to disambiguate from the user'sdomicile) is used to represent a collection of networked devices thatare cooperating to provide an application or service. An instance of aHOUSEHOLD is identified with a household 610 (or household identifier),though a HOUSEHOLD may be identified with a different area or place.

In certain embodiments, a household identifier (HHID) is a short stringor an identifier that is computer-generated to help ensure that it isunique. Accordingly, the network 610 can be characterized by a uniqueHHID and a unique set of configuration variables or parameters, such aschannels (e.g., respective frequency bands), SSID (a sequence ofalphanumeric characters as a name of a wireless network), and WEP keys(wired equivalent privacy or other security keys). In certainembodiments, SSID is set to be the same as HHID.

In certain embodiments, each HOUSEHOLD includes two types of networknodes: a control point (CP) and a zone player (ZP). The control pointcontrols an overall network setup process and sequencing, including anautomatic generation of required network parameters (e.g., WEP keys). Inan embodiment, the CP also provides the user with a HOUSEHOLDconfiguration user interface. The CP function can be provided by acomputer running a CP application module, or by a handheld controller(e.g., the controller 308) also running a CP application module, forexample. The zone player is any other device on the network that isplaced to participate in the automatic configuration process. The ZP, asa notation used herein, includes the controller 308 or a computingdevice, for example. In some embodiments, the functionality, or certainparts of the functionality, in both the CP and the ZP are combined at asingle node (e.g., a ZP contains a CP or vice-versa).

In certain embodiments, configuration of a HOUSEHOLD involves multipleCPs and ZPs that rendezvous and establish a known configuration suchthat they can use a standard networking protocol (e.g., IP over Wired orWireless Ethernet) for communication. In an embodiment, two types ofnetworks/protocols are employed: Ethernet 802.3 and Wireless 802.11g.Interconnections between a CP and a ZP can use either of thenetworks/protocols. A device in the system as a member of a HOUSEHOLDcan connect to both networks simultaneously.

In an environment that has both networks in use, it is assumed that atleast one device in a system is connected to both as a bridging device,thus providing bridging services between wired/wireless networks forothers. The zone player 606 in FIG. 6 is shown to be connected to bothnetworks, for example. The connectivity to the network 612 is based onEthernet and/or Wireless, while the connectivity to other devices 602,604 and 608 is based on Wireless and Ethernet if so desired.

It is understood, however, that in some embodiments each zone player606, 604, 602 may access the Internet when retrieving media from thecloud (e.g., Internet) via the bridging device. For example, zone player602 may contain a uniform resource locator (URL) that specifies anaddress to a particular audio track in the cloud. Using the URL, thezone player 602 may retrieve the audio track from the cloud, andultimately play the audio out of one or more zone players.

VI. Example System Configuration

FIG. 7 shows a system including a plurality of networks including acloud-based network and at least one local playback network. A localplayback network includes a plurality of playback devices or players,though it is understood that the playback network may contain only oneplayback device. In certain embodiments, each player has an ability toretrieve its content for playback. Control and content retrieval can bedistributed or centralized, for example. Input can include streamingcontent provider input, third party application input, mobile deviceinput, user input, and/or other playback network input into the cloudfor local distribution and playback.

As illustrated by the example system 700 of FIG. 7, a plurality ofcontent providers 720-750 can be connected to one or more local playbacknetworks 760-770 via a cloud and/or other network 710. Using the cloud710, a multimedia playback system 720 (e.g., Sonos™), a mobile device730, a third party application 740, a content provider 750 and so on canprovide multimedia content (requested or otherwise) to local playbacknetworks 760, 770. Within each local playback network 760, 770, acontroller 762, 772 and a playback device 764, 774 can be used toplayback audio content.

VII. Example Direct Routing-Enabled Zone Player

Certain particular examples will now be provided in connection withFIGS. 8-12 to describe, for purposes of illustration only, certainsystems, apparatus and methods that override a governing protocol toprovide and facilitate direct communication between nodes of a networkaudio system.

FIG. 8 shows an internal functional block diagram of an example directrouting-enabled zone player 800 including direct spanning tree protocolcontrol. The example zone player 800 of FIG. 8 may be used to implementany of the example zone players 102-124 of FIG. 1.

Like the example zone player 400 of FIG. 4, the example zone player 800of FIG. 8 includes a network interface 402 (including wireless 404 andwired 406 interfaces), a processor 408, a memory 410, an audioprocessing component 412, a module 414, an audio amplifier 416, speakers418, and one or more antenna(s) 420. These components are discussed inmore detail above. More or less components may be included depending onthe desired configuration.

The example zone player 800 of FIG. 8 further includes a direct routingenabler 822. The example direct routing enabler 822 of FIG. 8 enablesthe direct routing or linking of zone players and/or other nodes in anetwork. As described in detail below, the example direct routingenabler 822 evaluates a plurality of conditions to determine whether adirect link is to be utilized for particular frames and/or packets ofdata. That is, the example direct routing enabler 822 causes a node, incertain circumstances (e.g., presence of audio data, certain networkconfiguration parameters, etc.), to override blocking imposed by anetwork configuration protocol. In such instances, the node bypasses anintermediary node (e.g., a root node, etc.) and communicates directlywith a target node in contradiction with its bridge table settings. Insome examples, the direct routing enabler 822 enables a direct linkbetween nodes for only some type(s) of data, such as audio data, and notfor other type(s) of data, such as Internet data.

VIII. Example Network Configuration

FIG. 9 shows an example network 900 in which example methods andapparatus disclosed herein may be implemented. The example network 900of FIG. 9 supports a combination of wired and wireless links and/orinterfaces, as shown in the legend 901. The example network 900 includesfour nodes 902, 904, 906 and 908 and a router 910. In the illustratedexample, the nodes 902-908 correspond to media playback devices, such asthe zone players of FIGS. 1, 2A-C, 4, and/or 8. For the purpose ofdiscussion below, zone player (ZP) is used as a general term for allplayback devices that can participate in a spanning tree. However,example methods and apparatus disclosed herein can be implemented inconnection with any suitable type of device represented by the nodes902-908 of FIG. 9. The example router 910 is a Wi-Fi router thatsupports both wired and wireless communication. However, additional oralternative type(s) of routers can be utilized to facilitatecommunication in the network 900. In the illustrated example, the firstnode 902 is in communication with the router 910 and the second node 904via wired connections. Further, the first node 902 is in communicationwith the third node 906 and the fourth node 908 via wirelessconnections. As described in greater detail below, the nodes 902-908 arein communication with each other via one or more forwarding techniquesand/or configurations.

The example nodes 902-908 are controlled using any one of a plurality ofcontrollers 912 a-c. A first one of the controllers 912 a is implementedby a smart phone (e.g., an ANDROID® smart phone, an IPHONE®, etc.). Asecond one of the controllers 912 b is a desktop computer (e.g., a PC orMAC®). A third one of the controllers 912 c is a tablet device (e.g., anIPAD®). The example controllers 912 a-c of FIG. 9 correspond to, forexample, the example controller 130 of FIG. 1, controller 300 of FIG. 3and/or example controller 500 of FIG. 5. The example controllers 912 a-cof FIG. 9 implement an application configured to control the examplenodes 902-908. The example controller 912 a of FIG. 9 communicates withthe nodes 902-908 via a direct communication with node 902. The examplecontrollers 912 b-c of FIG. 9 communicate with the nodes 902-908 via theexample router 910.

Using the example network 900, the nodes 902-908 can share or exchangeone or more audio sources and be grouped to play the same or differentaudio sources. Additionally or alternatively, audio sources can beplaced in direct communication with the nodes 902-908. In some examples,the first node 902 and the second node 904 are grouped to playback onepiece of music, and at the same time, the third node 906 plays backanother piece of music. In other words, the nodes 902-908, as shown inFIG. 9, form a HOUSEHOLD that distributes audio and/or reproduces sound.As used herein, the term HOUSEHOLD (provided in uppercase letters todisambiguate from the user's domicile) is used to represent a collectionof networked devices that are cooperating to provide an application orservice.

The example network 900 of FIG. 9 utilizes a mesh networking topology toplace the nodes 902-908 in communication with each other. In addition toreceiving and processing data (e.g., rendering received audio data),nodes of a meshed network are sometimes required to act as a bridge orrelay to spread data to other nodes. Such a network configurationincreases the reachability of the individual nodes 902-908. The examplemesh network 900 of FIG. 9 is configured according to a spanning treeprotocol (STP). The spanning tree protocol is utilized by the examplenetwork 900 to implement a topology that does not include loops.

In certain examples, the mesh network 900 is based on IEEE 802.1dspanning tree protocol (STP) (with or without some proprietaryenhancements). The example mesh network 900 supports meshing over bothwired (e.g., wired interface 406) and wireless (e.g., wireless interface404) interfaces. For a wireless interface (e.g., at 2.4 GHz), ratherthan classifying the interface itself as a bridge port (e.g., as itwould be according to IEEE 802.1d), each peer zone player that isreachable through the interface is added as a port in the bridge (e.g.,in the bridge table). Zone players (ZP) classify these ports aspoint-to-point (p2p) and, among other things maintained for a p2p portentry, maintain an interface Media Access Control (MAC) address of acorresponding peer ZP. Traffic flowing through these ports isencapsulated in a p2p header and is forwarded as unicast frames, forexample.

For example, in FIG. 9 where the first node 902 is wired to both thesecond node 904 and the Wi-Fi router 910, the first node 902 includesfive port entries in its bridge table: two entries for its wiredinterface and three entries for its wireless neighbors (e.g., secondnode 904 (which also includes a wireless interface), third node 906, andfourth node 908). Port entries for the second node 904, third node 906,and fourth node 908 identify the nodes as p2p ports and maintaininformation about an interface MAC address for each node (e.g., used forencapsulation). For example, if the first node 902 is to forward a frametowards the third node 908, the first node 902 first encapsulates theframe in p2p a header with a recipient address of the header set to thewireless interface MAC address of the fourth node 908.

In certain examples, using STP as a forwarding algorithm can result intriangular routing. Triangular routing occurs if a device (e.g., a zoneplayer or other playback device) has a direct link to a neighbor but STPhas blocked the direct link to prevent routing loops. For example, inthe network 900 of FIG. 9, four nodes (e.g., zone players) are withincommunication range of each other. The first node 902 works as the rootof the spanning tree and has direct links to the second node 904, thirdnode 906, and fourth node 908. To prevent routing loops, the spanningtree protocol blocks the fourth node's 908 p2p port to the second node904 and the third node 906, and the third node's 906 p2p port to thesecond node 904. If the third node 906 has a frame destined for thefourth node 908, the third node 906 has to send the frame to the fourthnode 908 through the first node 902, which results in triangularrouting.

In certain examples, to prevent, reduce or minimize a possibility oftriangular routing in the mesh network 900, “direct routing” isdescribed and used herein for route optimization or improvement. Indirect routing, if a zone player has a unicast frame whose finaldestination is its neighbor and the neighbor itself is not next-hop in aspanning tree, then, rather than using the spanning tree to forward theframe, the frame can be directly sent using a unicast methodology to theneighbor. If the frame is forwarded to a multicast group, the zoneplayer also checks to see if remaining members of the multicast groupare its neighbors. If members of the group are its neighbors, then thezone player unicasts the frame to individual members of the multicastgroup rather than using the spanning tree, for example.

In certain examples, a determination of whether a zone player is aneighbor includes not only a network distance but also a signalstrength. For example, neighbors are to have sufficient wireless signalstrength for data communication between the neighbors.

In certain examples, rather than employing a strictly next-hop approach,a “least-hops” or “less-hops” approach can be employed. For example, ifdirect routing between zone players takes two hops but following the STPtakes three hops, then direct routing to take two hops is employed. Incertain examples, direct routing may be employed for certain types ofdata, rather than all data being routed. For example, audio data may beeligible for direct routing while other data may follow the STP.

The spanning tree protocol implements bridge tables at each of the zoneplayers 902-908 that define manners in which the respective zone playercommunicates with other zone players of the network 900. The bridgetables of the STP can be stored locally on the zone players 902-908 andare updated when, for example, a zone player is added to the network900, deleted from the network 900, and/or the network 900 is otherwisemodified. In some examples, the network 900 automatically configuresand/or reconfigures itself without input from a user. In such instances,the spanning tree protocol maintains a configuration that prevents datacommunication from looping. To prevent loops in the communication ofdata between the zone players 902-908, the bridge tables generated inaccordance with the spanning tree protocol include entries or settingsthat block direct communication between two zone players. That is, theloop-preventing aspects of the spanning tree protocol sometimes force acommunication path between two nodes to be bridged by an intermediarynode. The two nodes for which direct routing communication is prohibitedby the spanning tree protocol are referred to herein as “blocked” nodes.

FIG. 9 includes an example bridge table entry 914 of the fourth node 908of the example network 900. While the example bridge table entry 914 ofthe fourth node 908 is shown in FIG. 9, each of the other nodes 902-906includes a similar (but differently configured) bridge table entry. Inaddition to the information shown in FIG. 9, the bridge tables of thenodes 902-908 may contain other information for routing and/or otherpurposes. Further, although shown as a single table 914 in the exampleof FIG. 9, the information of the example table 914 can be implementedin one or more tables (e.g., a bridge table and a forwarding table). Theexample bridge table entry 914 defines communication paths between thefourth node 908 and the other nodes 902-906 of the network 900. As theexample nodes 902-908 of FIG. 9 correspond to zone players, the nodes902-908 include communication ports that are each capable ofestablishing a link with another node. The link at each port can bewired or wireless in the example of FIG. 9. The example bridge tableentry 914 maintains characteristics of the ports of the fourth node 908,thereby controlling the manner in which the fourth node 908 communicatesdata to and from the respective other nodes 902-906.

In the illustrated example, the bridge table 914 includes, for eachinterface of the fourth node 908, a port type, a local interfaceaddress, a remote interface address (e.g., remote MAC address), a portstate, a remote port state, an identification of the remote node (e.g.,remote Bridge ID), and a list of reachable nodes (e.g., a list of BridgeIDs) through the interface. The port type indicates whether thecorresponding link is a wired link or a wireless link. In the example ofFIG. 9, when the port type is a point-to-point (p2p) port, thecorresponding communication link is a wireless link. Thus, the examplebridge table entry 914 of FIG. 9 indicates that the fourth node is in orcan be in wireless communication with each of the other nodes 902-906.Conversely, the bridge table entry of the second node (not shown)includes at least one port entry corresponding to the first node 902that indicates a wired communication link.

The remote interface address (e.g., REMOTE INTERFACE) of the examplebridge table entry 914 identifies the corresponding node by adestination address (e.g., a MAC address) of the corresponding node. Theexample bridge table entry 914 shows the remote interface address foreach port with a name of the corresponding port. However, the name maybe representative of a numerical network address. The remote interfaceinformation is used to direct a frame of data to the proper one of theinterfaces of the proper one of the nodes 902-908. For example, when thefourth node 908 needs to forward data to the third node 906, the devicerepresented by the fourth node 908 encapsulates the frame in a p2pheader having a destination address set to the wireless remote interfaceaddress of the third node 906. As a result, as the frame of datatraverses the network 900, the nodes that are forwarding the frame areaware of the destination of the frame.

The port state and the remote state information of the example bridgetable entry 914 control whether or not the fourth node 908 can directlycommunication with the corresponding port. As mentioned above, thespanning tree protocol is implemented to prevent data from traversing aloop in the network 900. To do so, the spanning tree protocol blockscertain nodes from forwarding data directly to certain other nodes. Forexample, the bridge table 914 of FIG. 9 indicates that the fourth nodeis blocked from forwarding data directly to the second node 904. Thefourth node 908 is also blocked from forwarding data directly to thethird node 906. Further, the fourth node 908 is able to forward datadirectly to the first node 902 which, in the example of FIG. 9, is theroot node of the network 900. Thus, if the fourth node 908 needs totransmit data to the third node 906, the data is routed from the fourthnode 908 to the first node 902, and from the first node 902 to the thirdnode 906. Similarly, if the fourth node 908 needs to transmit data tothe second node 904, the data routed from the fourth node 908 to thefirst node 902, and from the first node 902 to the second node 904.

While such a configuration is useful for preventing looping of data andthe drawbacks thereof, the blocking of the links enforced by thespanning tree protocol also results in longer communication paths fordata. For example, the requirement of the fourth node 908 to route datato the third node 906 through the first node 902 can be consideredtriangular routing. The triangular route between the fourth node 908 andthe third node 906 is longer than a direct route or link between thefourth node 908 and the third node 906. Such a direct route is shown inthe example of FIG. 9 as a direct wireless link 916. The example directrouting enabler 822 of FIG. 8 enables the direct route or link 916 ofFIG. 9. As described in detail below, the example direct routing enabler822 evaluates a plurality of conditions to determine whether the directlink 916 (and/or other direct links in the network 900) is to beutilized for particular frames and/or packets of data. That is, theexample direct routing enabler 822 causes the fourth node 908, incertain circumstances, to override the blocking imposed by the networkconfiguration protocol of the network 900. In such instances, the fourthnode 908 bypasses the first node 902 and communicates directly with thethird node 906 in contradiction with the settings of the bridge tableentry 914. In some examples, the enablement of the direct link 916 isconfigured for some type(s) of data, such as audio data, and not forsome type(s) of data, such as Internet data.

IX. Example Direct Communication

FIG. 10 is an example implementation of the direct routing enabler 822of FIG. 8. For purposes of illustration, the example direct routingenabler 822 of FIG. 10 is described below as implemented at the examplefourth node 908 of FIG. 9. However, the example direct routing enabler822 of FIG. 8 and/or 10 can be implemented in any of the nodes 902-908of FIG. 9 and/or other node(s) of alternative network(s). The exampledirect routing enabler 822 enables the example direct link 916 of FIG. 9and/or any other direct link(s) between the nodes 902-908 of FIG. 9.

The example direct routing enabler 822 of FIG. 10 includes a signalstrength monitor 1000 to detect and/or evaluate quality and/orreliability of wireless communication links between the nodes 902-908.In the illustrated example, the nodes 902-908 undergo a learning phasewhen introduced into the network 900. When the example signal strengthmonitor 1000 initially detects one of the other nodes 902-906, theexample signal strength monitor 1000 causes an entry to be added andpopulated in the bridge table entry 914. A program or applicationimplementing the spanning tree protocol is executed to generate thesettings to populate the new entry of the bridge table of the network900. That is, the spanning tree protocol determines whether, forexample, the detected node can communicate directly with the fourth node908. After the network configuration protocol information has beenpopulated in the table 914, the example signal strength monitor 1000determines whether the wireless links of the table 914 have a strength(e.g., via remote signal strength indication (RSSI) monitoring)indicative of a high quality link. In other words, the example signalstrength monitor 1000 tests the wireless link(s) between fourth node 908and the other nodes 902-906 to determine whether the wireless link(s)can be trusted for direct communication (e.g., routing audio data).

For each of the wireless ports of the table 914, the example signalstrength monitor 1000 enables direct communication (e.g., for the directlink 916 of FIG. 9) if the corresponding signal strength between therespective nodes is above a threshold. The threshold may be, forexample, twenty-five decibels (dB). The enablement of directcommunication for a certain port (e.g., the wireless interface port ofthe third node 906) is recorded via, for example, a flag in thecorresponding entry of the bridge table 914 and/or any other datastructure associated with the fourth node 908 and/or the network 900.Further, the example signal strength monitor 1000 continues to monitorthe signal strength of the wireless links. If the strength of a wirelesslink that has been enabled for direct communication drops below thethreshold, the example signal strength monitor 1000 of FIG. 10 disablesthe corresponding direct communication (e.g., by toggled thecorresponding flag of the table 914). Thus, enablement of, for example,the direct link 916 of FIG. 9 can fluctuate depending on the signalstrength of the wireless link between the fourth node 908 and the thirdnode 906. In certain examples, the threshold to maintain a directcommunication link may differ from the threshold to add a directcommunication link (e.g., 19 dB to maintain a direct communication linkand 25 dB to add a direct communication link, and so on).

The example direct routing enabler 822 includes a maintenance framedetector 1002 to determine whether a frame of data corresponding tonetwork maintenance information. As described above, networkconfiguration settings associated with, for example, the network 900 ofFIG. 9 is updated on an on-going basis. To help ensure that networkconfiguration information is properly updated throughout the network900, one or more of the nodes 902-908 periodically transmits maintenanceframe(s). The periodicity of the maintenance frame(s) can be based on,for example, a maximum age value (e.g., which is a timer that controlsthe maximum length of time that passes before a bridge port savesconfiguration information) of a corresponding STP node. The maintenanceframe(s) are to be routed through the network 900 according to thenetwork protocol settings (e.g., the spanning tree protocol settings)regardless of an enabled direct communication link. For example, whenthe fourth node 908 receives a maintenance frame, the fourth node 908routes the frame to the third node 906 (if the frame is directed to thethird node 906) according to the “blocked” setting of the table 914. Inother words, despite the enablement of the direct link 916 of FIG. 9,the fourth node 908 directs frames identified by the detector 1002 asmaintenance frames to the third node 906 via the first node 902. Thisensures that the first node 902 is exposed to any network configurationupdates intended for the first node 902 when the first node 902 may haveotherwise been bypassed by the direct routing enabler 822.

Additional or alternative techniques can be utilized to ensure thatnetwork configuration information is properly updated throughout thenetwork 900. For example, the direct routing enabler 822 can disable thedirect route provided thereby for a number of frames (e.g., one frameout of every one hundred frames). When the direct route is disabled, theframes are sent through the STP communication path. In such instances,if data arrives at one or more devices out of order, the data can bereassembled. Additionally or alternatively, the example direct routingenabler 822 and/or any other suitable component of the example zoneplayer 800 can periodically send a duplicate frame through the STPcommunication path. In such instances, the duplicate frame can bediscarded.

To determine whether received data (e.g., a packet of data, a frame ofdata, a group of packets, etc.) is to be directly communicated to adestination node despite a network protocol setting indicating that thedata is to be indirectly communicated (e.g., via an intermediary node),the example direct routing enabler 822 includes a bridge table analyzer1004 having a wireless interface detector 706 and a direct port detector1008, a logical distance calculator 1010, and an overrider 1012. As theexample direct routing enabler 822 receives frame(s) of data, theexample bridge table analyzer 1004 of FIG. 10 analyzes the table of thecorresponding node of the network with respect to the received frame(s).In the illustrated example, when the fourth node 908 receives a dataframe, the example bridge table analyzer 1004 analyzes the example table914 of FIG. 9. In particular, the example bridge table analyzer 1004determines what type of port the fourth node 908 is set to use forforwarding the received frame and whether or not a destination node ofthe frame is available to the fourth node 908 via a direct port (e.g.,is a neighbor of the fourth node).

To determine what type of port the fourth node 908 is to use to forwardthe frame, the example wireless interface detector 1006 determineswhether the appropriate forwarding port corresponds to a wired interfaceor a wireless interface. As the forwarding ports of the fourth node 908are each a wireless interface, the wireless interface detector 1006determines that the appropriate forwarding port for the example receivedframe is a wireless port. However, another instance of the wirelessinterface detector 1006, such as one associated with the second node 904of FIG. 9, may determine that the appropriate forwarding port is a wiredinterface. In the example of FIG. 10, for the direct routing enabler 822enables the direct communication disclosed herein (e.g., the direct link916 of FIG. 9) when the appropriate forwarding port is determined to bea wireless link or interface. Further, the direct routing enabler 822does not enable the direct communication disclosed herein when theappropriate forwarding port is determined to be a wired link orinterface. To implement this configuration, the example wirelessinterface detector 1006 generates an indication of its findings for theframes of data received at the direct routing enabler 822, which is usedby the direct routing enabler 822 to activate and/or deactivate thedirect links used to override a governing network protocol that isotherwise blocking the direct links.

The example direct port detector 1008 extracts a destination address ofthe received frame of data (e.g., a from a frame header) to determinewhether the destination node is directly accessible by the fourth node908. That is, the example direct port detector 1008 determines whetherthe receiving node has a direct link with the node at which the receivedframe is destined to be transmitted. In the illustrated example, thedirect port detector 1008 compares the destination address of thereceived frame to the remote Bridge ID of the bridge table entry 914. Asdescribed above, the bridge table entry 914 of the fourth node 908includes a p2p entry for each node wirelessly sensed by the fourth node(e.g., via the signal strength monitor 1000). Therefore, in theillustrated example, if the bridge table entry 914 includes an entryhaving a remote Bridge ID matching the destination address of thereceived frame, the direct port detector 708 determines that the fourthnode 908 includes a direct link with the destination node of thereceived frame. In the example of FIG. 10, the direct routing enabler822 enables the direct communication disclosed herein (e.g., the directlink 916 of FIG. 9) for frames of data when the node receiving theframes is in direct communication with the destination node of theframes. Further, the example direct routing enabler 822 of FIG. 10 doesnot enable the direct communication disclosed herein for frames of datawhen the node receiving the frames lacks a direct communicationinterface with the destination node of the frames. Therefore, theexample direct port detector 1008 generates an indication of itsfindings for the frames of data received at the direct routing enabler822, which is used by the direct routing enabler 822 to activate and/ordeactivate the direct links used to override a governing networkprotocol that is otherwise blocking the direct links.

Accordingly, for a frame of data received at the fourth node 908, theexample bridge table analyzer 1004 generates a first indication that thefourth node 908 uses (or does not use) a wireless interface (e.g.,logical port) to forward the received frame, and a second indicationthat the fourth node 908 has (or does not have) a direct link with adestination node of the received frame.

The logical distance calculator 1010 of the example direct routingenabler 822 of FIG. 10 determines whether received frames of data are“next-hop” frames. As used herein, a “next-hop” frame of data is onethat is configured to arrive at its final destination node upon its nexthop according to a governing network protocol that defines acommunication path for the frame of data. In other words, if a networkprotocol (e.g., as defined by bridge tables in an STP network) indicatesthat the frame is set to not be forwarded by the next node in thecorresponding communication path, the frame is designated as a“next-hop” frame. For example, the spanning tree protocol governing theexample network 900 of FIG. 9 defines a communication path through thefirst node 902 for a frame of data at the fourth node 908 destined for(e.g., have a destination address of) the second node 904. Such a frameis not a “next-hop” frame while at the fourth node 908. However, theframe is a “next-hop” frame while at the first node 902 because thesubsequent node in the STP communication path is the destination node(the second node 904).

To determine whether a received frame of data is a “next-hop” frame, theexample logical distance calculator 1010 analyzes the destination forthe received frame to determine if there is a remote Bridge ID entrymatching that destination in the bridge table. If the destinationaddress of the frame is the next node in the communication path, thelogical distance calculator 1010 determines that the logical distancefor the frame is one hop. On the other hand, if the destination addressof the frame is not the next node in the communication path, the logicaldistance calculator 1010 determines that the logical distance for theframe is greater than one hop. In some examples, the logical distancecalculator 1010 determines whether the logical distance is or is notgreater than one hop. That is, the example logical distance calculator1010 determines whether or not the logical distance of the frame to thedestination node is greater than a threshold (e.g., one hop).Alternatively, the example logical distance calculator 1010 candetermine and/or record the number of hops.

When the example logical distance calculator 1010 determines that theframe is a “next-hop” frame, the example direct routing enabler 822 doesnot enable the direct link disclosed herein because the governingnetwork protocol that would be overridden by the direct link alreadyaccomplishes the communication of the direct link. That is, enablementof the direct link (e.g., the link 916 of FIG. 9) would not bypass anyintermediary node when the frame is a “next-hop” frame. Therefore, insuch instances, the direct routing enabler 822 allows the governingprotocol communication path to be followed. On the other hand, when theframe is not a “next-hop” frame, the example direct routing enabler 822does enable the direct link disclosed herein. Thus, the example logicaldistance calculator 1010 generates an indication of its findings for useby the direct routing enabler 822 in activating and/or deactivating theappropriate direct link(s).

While the above example is illustrated with respect to a “next-hop”frame, the direct routing enabler 822 can enable direct routing betweennodes in a communication path where a direct routing approach is fasterthan a spanning tree approach (e.g., direct routing is a two-hop pathwhile the STP provides a three-hop path). Alternatively or in addition,the direct routing enabler 822 can determine whether STP-only, directrouting for next-hop nodes, direct routing for shorter hop nodes, directrouting for certain types of data (e.g., audio), etc., is employed.

The example overrider 1012 of FIG. 10 receives information from thesignal strength monitor 1000, the maintenance frame detector 1002, thebridge table analyzer 1004, and the logical distance calculator 1010indicative of whether direct communication that contradicts thegoverning network protocol settings should be used in connection with acorresponding frame or frames of data. If the indications and/ordetections described above in connection with the signal strengthmonitor 1000, the maintenance frame detector 1002, the bridge tableanalyzer 1004, and the logical distance calculator 1010 indicate thatthe direct communication should bypass the communication path defined inthe governing network protocol (e.g., the bridge table entries 914), theexample overrider 1012 replaces a destination port of the frame(s) withthe destination address of the frame(s). That is, when a received frameat the fourth node 908 is configured by the spanning tree protocoltables to be routed to the third node 906 via the first node 902, theframe is encapsulated in a p2p header having a destination address setto the wireless remote interface address corresponding to the first node902 and a destination address in the original frame still correspondingto the third node 906. The example overrider 1012 (when authorized to doso by the other components of the direct routing enabler 822) replacesthe destination address in the encapsulated p2p header corresponding tothe intermediary node (e.g., the first node 902) with the destinationaddress set to the wireless remote interface address of the final node(e.g., the third node 906). Further, the example overrider 1012designates the frame as a special type of frame referred to herein as an“ether frame.” An “ether frame” is one that the overrider 1012 hasmanipulated to override or bypass the communication path defined by thespanning tree protocol tables. In some examples, the special type offrame designation prevents the destination node from updated thegoverning network protocol settings (e.g., table entries) based onframes that are received via the direct routing override disclosedherein. Further, the example overrider 1012 does not alter the networkprotocol settings that define the spanning tree protocol communicationpath involving the fourth node 908. Instead, the frames of data aredirectly routed to the destination node without changing the settings ofthe governing network protocol.

Although the above description refers to unicast frames, which have asingle destination address, the frames received at the nodes 902-908 canalternatively be multicast frames, which have a multi-cast group ID usedfor more than one destination address. For multicast frames, the exampledirect routing enabler 822 evaluates each of the destination addressesof the multicast group to determine whether a direct link should be usedto communicate the data to respective nodes of the multicast frame. Insome examples, the direct routing enabler 822 can enable a direct linkfor a first node of the multicast frame and not a second node of themulticast frame. Alternatively, the direct routing enabler 822 mayrequire each of the destination nodes to qualify for a direct link.

While an example manner of implementing the direct routing enabler 822of FIG. 8 has been illustrated in FIG. 10, one or more of the elements,processes and/or devices illustrated in FIG. 10 may be combined,divided, re-arranged, omitted, eliminated and/or implemented in anyother way. Further, the example signal strength monitor 1000, theexample maintenance frame detector 1002, the example bridge tableanalyzer 1004, the example wireless interface detector 1006, the exampledirect port detector 1008, the example logical distance calculator 1010,the example overrider 1012, and/or, more generally, the example directrouting enabler 822 of FIG. 10 may be implemented by hardware, software,firmware and/or any combination of hardware, software and/or firmware.Thus, for example, any of the example signal strength monitor 1000, theexample maintenance frame detector 1002, the example bridge tableanalyzer 1004, the example wireless interface detector 1006, the exampledirect port detector 1008, the example logical distance calculator 1010,the example overrider 1012, and/or, more generally, the example directrouting enabler 822 of FIG. 10 could be implemented by one or morecircuit(s), programmable processor(s), application specific integratedcircuit(s) (ASIC(s)), programmable logic device(s) (PLD(s)) and/or fieldprogrammable logic device(s) (FPLD(s)), field programmable gate array(FPGA), etc. When any of the appended claims are read to cover a purelysoftware and/or firmware implementation, at least one of the examplesignal strength monitor 1000, the example maintenance frame detector1002, the example bridge table analyzer 1004, the example wirelessinterface detector 1006, the example direct port detector 1008, theexample logical distance calculator 1010, the example overrider 1012,and/or, more generally, the example direct routing enabler 822 of FIG.10 are hereby expressly defined to include a tangible computer readablemedium such as computer readable storage medium (e.g., a memory, DVD,CD, Blu-ray, etc. storing the software and/or firmware). Further still,the example direct routing enabler 822 of FIG. 10 may include one ormore elements, processes and/or devices in addition to, or instead of,those illustrated in FIG. 10, and/or may include more than one of any orall of the illustrated elements, processes and devices.

Flowcharts representative of example machine readable instructions forimplementing and/or to be implemented with the example direct routingenabler 822 of FIGS. 8 and/or 10 are shown in FIGS. 11 and 12. In theexamples of FIGS. 11 and 12, the machine readable instructions comprisea program for execution by a processor such as the processor 408 of FIG.4. The program may be embodied in software stored on a tangible computerreadable medium such as a CD-ROM, a floppy disk, a hard drive, a digitalversatile disk (DVD), a Blu-ray disk, or a memory associated with theprocessor 408, but the entire program and/or parts thereof couldalternatively be executed by a device other than the processor 408and/or embodied in firmware or dedicated hardware. Further, although theexample programs are described with reference to the flowchartsillustrated in FIGS. 11 and 12, many other methods of implementing theexample direct routing enabler 822 may alternatively be used. Forexample, the order of execution of the blocks may be changed, and/orsome of the blocks described may be changed, eliminated, or combined.

FIG. 11 begins with receipt of one or more frames of data, such as audiodata, at one of the nodes 902-908 of FIG. 9 (block 1100). The receivedframe(s) can be data packets, a single frame of data, a group of datapackets, etc. For purposes of illustration, FIG. 11 is discussed withreference to the frame(s) of data being received at the fourth node 908of FIG. 9. The example maintenance frame detector 1002 (FIG. 10)determines whether the received frame(s) are maintenance frame(s) sentover the network 900 (FIG. 9) to maintain network configuration settings(block 1102). If the maintenance frame detector 1002 determines that thereceived frame(s) include a maintenance frame, the maintenance framedetector 1002 generates an indication that the governing networkprotocol is to be used to forward the frame(s) and control proceeds toblock 1116. Otherwise, if the maintenance frame detector 1002 determinesthat the received frame(s) do not include a maintenance frame, acorresponding indication is generated and control proceeds to block1104.

The example wireless interface detector 1006 (FIG. 10) determineswhether the forwarding port to be used by the fourth node 908 to forwardthe received frame(s) is a wireless interface (block 1104). To do so,the example wireless interface detector 1006 analyzes the bridge tableentry 614 (FIG. 6) to determine whether the fourth node 608 forwards thereceived frame(s) via, for example, a p2p port, which is indicative of awireless interface being utilized. If the wireless interface detector1006 determines that the forwarding port of the fourth node 908 is awired interface, the wireless interface detector 1006 generates anindication that the governing network protocol is to be used to forwardthe frame(s) and control proceeds to block 1116. Otherwise, if thewireless interface detector 1006 determines that the forwarding port ofthe fourth node 908 is a wireless interface, a corresponding indicationis generated and control proceeds to block 1106.

The example logical distance calculator 1010 (FIG. 10) determineswhether the received frame(s) are “next-hop” frame(s) (block 1106). Todo so, the example logical distance calculator 1010 calculates a numberhops remaining in a communication path defined by the governing networkprotocol settings. If the logical distance calculator 1010 determinesthat the received frame(s) are “next-hop” frame(s), the logical distancecalculator 1010 generates an indication that the governing networkprotocol is to be used to forward the frame(s) and control proceeds toblock 1116. Otherwise, if the logical distance calculator 1010determines that the received frame(s) are not “next-hop” frame(s), acorresponding indication is generated and control proceeds to block1108.

While the above example is illustrated with respect to a “next-hop”frame, the logical distance calculator 1010 can determine whether anumber of hops to deliver a frame via direct routing is less than anumber of hops to deliver the frame via the spanning tree protocol(e.g., direct routing is a two-hop path while the STP provides athree-hop path). If the number of hops via direct routing is less thanthe number of hops via STP, then direct routing proceeds as with thenext-hop approach, for example.

The example direct port detector 1008 (FIG. 10) determines whether thebridge table entry 914 of the fourth node 908 includes a port with abridge identifier (e.g., in the remote interface field) that matches thedestination address of the received frame(s) (block 1108). In otherwords, the example direct port detector 1008 determines whether thedestination node of the received frame(s) are neighbor(s) (e.g.,accessible via a direct wireless communication without use of anintermediary node) of the fourth node 908. If the direct port detector1008 determines that the table 914 does not include a matching port, thedirect port detector 1008 generates an indication that the governingnetwork protocol is to be used to forward the frame(s) and controlproceeds to block 1116. Otherwise, if the direct port detector 1008determines that the table 914 includes a matching port (e.g., that thefourth node 908 and the destination node are neighbors), a correspondingindication is generated and control proceeds to block 1110.

An output of the example signal strength monitor 1000 (FIG. 10) ischecked to determine whether the direct link for bypassing the governingnetwork protocol is enabled based on the signal strength of the wirelesslink between the fourth node 908 and the destination node of thereceived frame(s) (block 1110). FIG. 12 illustrates an exampleimplementation of block 1110 of FIG. 11. The example of FIG. 12 beginswhen the signal strength monitor 1000 and/or another learning componentof a first node (e.g., the fourth node 908) learns of a second node inthe network 900 (e.g., the third node 906) via wireless communication(e.g., by receiving RSSI data) (block 1200). The example signal strengthmonitor measures the corresponding signal strength between the firstnode and the second node by, for example, calculating an average numberof valid RSSI messages exchanged between the first and second nodes overa period of time (block 1202). If the measuring signal strength isgreater than a threshold (e.g., twenty-five dB) (block 1204), the signalstrength monitor 1000 enables direct communication between the first andsecond nodes (block 1206). Otherwise, the signal strength monitor 1000disables direct routing between the first and second nodes (block 1208).The example signal strength monitor 1000 repeatedly (e.g., continuously)monitors the signal strength and updates the enablement or disablementof the direct communication accordingly. Thus, while the direct routingdisclosed herein between two nodes may be enabled at a first time, thedirect routing can be disabled and re-enabled at second and third times.

Referring back to FIG. 11, if the direct routing is not enabled (e.g.,disabled, not enabled for the type of frame, unavailable due to lack ofsignal strength, etc.) for the destination node of the received frame(s)(block 1110), the signal strength monitor 1000 generates an indicationthat the governing network protocol is to be used to forward theframe(s) and control proceeds to block 1116. Otherwise, if the signalstrength monitor 1000 determines that the direct routing is enabled forthe destination node, a corresponding indication is generated andcontrol proceeds to block 1112.

When control proceeds to block 1112, the example overrider 1012 sets thedestination address to be the remote interface address of thedestination address of the received frame (block 1112). In someexamples, the overrider 1012 additionally designates the receivedframe(s) as a special type of frame (e.g., an ether frame) by, forexample, setting a flag in the table 914 and/or another data structureassociated with the corresponding frame(s) and/or node(s). With theoverrider 1012 having replaced the destination information of thereceived frame(s) to cause the direct routing thereof, the exampledirector communication enabler 822 bypasses the communication pathdefined by the governing network protocol and, instead, forwards thereceived frame(s) directly to the destination node (block 1114).Otherwise, if control has proceeded to block 1116, the communicationpath defined by the governing network protocol (e.g., spanning treeprotocol) is used to forward the received frame(s) (block 1116). Theexample of FIG. 11 then ends (block 1118).

X. Example Multicast Direct Routing

In certain examples, to convey data over a playback network, multicastand unicast routing can be supported. Rather than a unicast message fromone node to another node, a multicast message from one node to aplurality of nodes can be transmitted via direct routing if certainconditions are satisfied (e.g., allowable data type (e.g., audio dataand so on), acceptable signal strength, appropriate bridge tableinformation, and so on). For example, if a node is transmitting amessage to a zone group (e.g., as a member of the group or as adistribution node providing content to the zone group), the node canmulticast the message to some or all of the nodes in the group insteadof or in addition to a direct unicast message to a single node.

For example, a zone player or other playback device transmits audio andplayback timing information in messages over a network using amulti-cast message transmission methodology. In some examples, each ofthe messages includes a multicast address (or some other ID oridentifying address) that is used to identify the multicast group ormembers of the multicast group for which the message is intended. Eachdevice associated with the group monitors the messages on the network,and, when a group member detects a message with its address or amulticast group address to which the device belongs, the device receivesand processes the contents of the message. It is understood, however,that the zone player or other playback device may make use of anyconvenient multicast or unicast (or other) message transmissionmethodology in transmitting the audio and playback timing information toother devices, for example.

In certain examples, audio and playback timing information is providedin the form of a series of frames, with each frame having a timestamp.The timestamp indicates a time, relative to the time indicated by aclock maintained by the playback device or some other designatedreference device, at which the frame is to be played. Depending on thesize or sizes of the messages used in the selected multi-cast messagetransmission methodology and the size or sizes of the frames, a messagemay contain one frame, or multiple frames, or, alternatively, a framemay extend across several messages. It is understood that theinformation included in the timestamp(s) may alternatively be providedby one device to other member playback devices in periodic ornon-periodic intervals instead of, or in addition to, in a series offrames.

As disclosed above, each node (e.g., zone player or other media playbackdevice) maintains one-hop wireless neighbor information in a neighbortable for unicast direct routing support. In certain examples, tosupport multicast direct routing, as well as unicast direct routing,each node also maintains information regarding whether any of itsneighbors has a wired port in a forwarding state. In certain examples, anode may maintain n-hop “neighbor” information to facilitate directrouting if allowed (e.g., if a number of hops n to a target node via“direct” routing is less than a number of hops to the node via STP orother indirect routing protocol).

In certain examples, to facilitate multicast direct routing, each nodeadvertises if it has a wired port in a forwarding state. For example, anode (e.g., a node 902-908) advertises that it has a wired port in aforwarding state using an independent message, through an IEEE 802.11Information Element (IE) in existing discovery probes, and so on. Framesare sent as a broadcast to all active node wireless interface(s). Forexample, even if a wireless interface for a node is blocked according toa spanning tree protocol, the wireless interface can be reached by theadvertising frame.

a. Example Multicast Frame Forwarding

To facilitate multicast routing to forward one or more message frames, amulticast address is selected. In certain examples, after a reboot, eachnode randomly selects a multicast IP address as its group address. Thenode uses this address as its multicast group address whenever the nodeworks as a Group Coordinator (GC) and has more than one Group Member(GM).

Multicast frame forwarding can be applied or not applied to a message tobe transmitted based on one or more rules and/or other criterion. Forexample, the GC uses multicast forwarding only if it has more than oneGM in its zone. Otherwise, the node forwards the traffic to another nodeas a unicast message. Thus, the GC may determine a number of groupmembers in its group and thereby determine whether to use multicastdirect routing, unicast direct routing, forwarding according to STP, andso on.

During its course of operation, a node can be GC of more than one zonegroup. In certain examples, for all zones in which a node (e.g., a zoneplayer or other media playback device) serves as a GC, that node usesthe same address as its multicast group address for each group. In otherexamples, the GC may establish different group addresses to distinguishbetween its different groups.

In certain examples, traffic streamed from the Internet or networkattached storage to the GC is delivered using a transmission controlprotocol (TCP). The GC then timestamps the frame (e.g., for synchronizedplay) and sends the frame to other GM(s). Traffic from the GC to GMs isdelivered using a network protocol such as a user datagram protocol(UDP), etc.

b. Example Group Join

In a playback system, a node may dynamically join and disengage from oneor more zones or zone groups. In certain examples, when a node (e.g.,zone player or other media playback device 800, 902, 904, 906, 908)joins an existing zone, the joining node works as a GM. If the zonegroup has more than one GM, the GC informs each GM about a multicastgroup it is to join (e.g., through a UPnP message). Once a GM receivesthe information about the multicast group it is to join (e.g., an IP orMAC address, and so on), the node creates a socket to receive themulticast traffic.

Once the node knows a multicast address to join, the node sends itsmulticast membership information in the local area network (LAN) throughone or more dedicated messages, for example. In certain examples,dedicated membership messages are sent with etherType set to 0x6970 anddestination set to 01:0E:58:DD:DD:DD. By setting bit 0 of the MACaddress to 1, a multicast destination is indicated.

Dedicated messages used to configure group membership include a list ofmulticast group addresses to which the node is attempting to subscribe,such as a single multicast address. The source address of this messageis set to the bridge ID of the node, for example.

The multicast membership message is forwarded throughout the LAN and isused to create a multicast forwarding entry at each node in the network(e.g., each zone player in the household, etc.). In certain examples,each node uses hashing to create a multicast forwarding entry for amulticast group address in a bridge table for the node. For eachmulticast forwarding entry, the node maintains a bridge port at whichthe node has received a membership request as well as a list of MACaddresses (e.g., bridge IDs in this case) that are subscribed to themulticast group.

c. Example Frame Forwarding

When a bridge or other node receives a frame (e.g., an Ethernet Layer 2(L2) frame) with destination address set to the multicast group address,the node first checks its multicast forwarding table to find the port(s)associated with members subscribed to the multicast group. For a givenoutgoing port with GM(s), the frame is forwarded through the portaccording to one or more conditions. For example, the frame is forwardedto a multicast group member if the following conditions are met: 1) theoutgoing port under consideration is in the forwarding state; 2) theoutgoing port under consideration is not the port at which the nodereceived the multicast frame in the first place (e.g., outgoing port isnot equal to incoming port); and 3) for p2p ports, the other end of thetunnel is in the forwarding state.

In certain examples, if the port is a p2p port (e.g., a wireless STPlink), the node sends a copy of the multicast data tunneled to the otherend of the p2p port. If the port is not p2p, the node reviews the listof MAC addresses currently subscribed to the multicast group through theport and sends a unicast copy to each of the subscribed nodes. Thus,once a multicast frame hits a wired link, forwarding of the multicastframe from that point on is as a unicast frame.

The messaging process can be repeated at each intermediate hop in anetwork until the frame is delivered to all participating members.

d. Example of Group Disengagement

Zone players and/or other nodes may dynamically switch groups, sometimesonly temporarily (e.g., for a certain zone configuration such as a sceneor theme that is time- and/or other constraint-limited, etc.). When adevice leaves or disengages from a zone group, port and/or otherinformation enabling the device to be connected to and/or otherwisereceive and process messages intended for the group are to be updated.In certain examples, when a GM switches its group, old port entriesexpire and are deleted after a period of time. In certain examples, anode sends a message to indicate that the node is leaving a group. Incertain examples, a follow-up message is sent to announce a group towhich the node now belongs (if any).

e. Example Reliability Determination

Given synchrony and/or other QoS constraints that may apply to aplayback network, reliability of message delivery may be important. Incertain examples, sequence numbers are used with UDP (unicast ormulticast) messages and/or other format messages to help ensure reliabledelivery of messages to GM(s). A GM can examine a message's sequencenumber to determine if it has missed delivery of a message, for example.If a GM misses a multicast frame (e.g., determined by checking sequencenumber), the node sends a negative acknowledgement to the GC requestingretransmission of the multicast frame (e.g., retransmitted as unicast),for example.

f. Example of Multicast Forwarding Network Operation

FIG. 13 illustrates an example network 1300 providing multicast frameforwarding. The example network 1300 of FIG. 13 supports a combinationof wired and wireless links and/or interfaces configured to conveyunicast and/or multicast messages, as shown in the legend 1301. Theexample network 1300 includes four nodes 1302, 1304, 1306 and 1308 and arouter 1310. In the illustrated example, the nodes 902-908 correspond tomedia playback devices, such as the zone players of FIGS. 1, 2A-C, 4,and/or 8. For the purpose of discussion below, zone player (ZP) has beenused as a general term for all playback devices that can participate ina spanning tree. However, example methods and apparatus disclosed hereincan be implemented in connection with any suitable type of devicerepresented by the nodes 1302-1308 of FIG. 13. The example router 1310is a Wi-Fi router that supports both wired and wireless communication.However, additional or alternative type(s) of routers can be utilized tofacilitate communication in the network 1300.

In the example of FIG. 13, a first node 1302 (e.g., a zone player orother media playback device, etc.) is designated as a root of a spanningtree for the network 1300. The second node 1304, third node 1306, andfourth node 1308 have a direct link to the first node 1302. In theexample network 1300, a link between the first node 1302 and the secondnode 1304, between the first node 1302 and the third node 1306, andbetween the first node 1302 and the fourth node 1308 are p2p wirelesslinks.

In the example network 1300 of FIG. 13, the third node 1306 works as theGC with the second node 1304 and the fourth node 1308 operating as GMs.Since the group includes more than one GM, the third node 1306 informsthe second node 1304 and the fourth node 1308 that the third node 1306is going to use a multicast message to deliver traffic and correspondingmulticast group information. Once the multicast information is in place(e.g., through join information sent from the second node 1304 and thefourth node 1308), each node in the network 1300 (e.g., a LAN) is awareof the currently active multicast group and members subscribed to thegroup.

Using the example network 1300 of FIG. 13, a user can play music througha device, such as a NAS server, storing media content. Music traffic isfirst sent as a unicast message to the third node 1306 using TCP. Asillustrated in the example of FIG. 13, music or other media content issent from a desktop controller 1312 to the router 1310 in a firstunicast message 1321. The router 1310 relays the content message to thefirst node 1302 via a second unicast message 1322. The first node 1302then sends the content message to the third node 1306 via a thirdunicast message 1323.

The third node 1306 timestamps the frame (e.g., for synchronizedplayback) and tries to deliver the frame for output using multicastmessaging. The third node 1306 consults its multicast table to find listof ports that have members subscribed to the multicast group. In theexample of FIG. 13, the third node 1306 discovers that it has twomembers (the second node 1304 and the fourth node 1308) for themulticast group, and the nodes 1304, 1308 are reachable through the samep2p port (e.g., the first node 1302). The third node 1306 thenencapsulates the multicast frame in a p2p header and forwards the frameto the first node 1302 via a multicast message 1324.

When the first node 1302 receives the encapsulated frame of themulticast message 1324, the node 1302 removes the p2p header and checksthe destination address of the frame. In the example of FIG. 13, thedestination address is a multicast address. The first node 1302 checksits multicast forwarding table to find the list of ports having memberssubscribed to the multicast group. In this case, the first node 1302determines that it has two p2p ports, a wireless port for the secondnode 1304 and a wireless port for the fourth node 1308. For these p2pports, the first node 1302 encapsulates the frame in a p2p header andforwards the frame as a multicast message (e.g., a multicast message1325(a) to the fourth node 1308 and a multicast message 1325(b) to thesecond node 1304). This process repeats until the frame is received byall group members (e.g., both the second node 1304 and the fourth node1308), for example.

g. Example of Multicast Forwarding Optimization

Multicast forwarding may also suffer from triangular routing due to useof a spanning tree protocol. For example, in FIG. 13, the second node1304 and the fourth node 1308 are neighbors of the third node 1306, butthe multicast traffic has to flow through the first node 1302 becauseSTP has blocked a direct link between the pairs a) third node1306—second node 1304 and b) third node 1306—fourth node 1308 to helpprevent routing loops.

While an example manner of implementing a direct routing multicastnetwork 1300 has been illustrated in FIG. 13, one or more of theelements, processes and/or devices illustrated in FIG. 13 may becombined, divided, re-arranged, omitted, eliminated and/or implementedin any other way. Further, one or more elements, processes and/ordevices of FIG. 13 may be implemented by hardware, software, firmwareand/or any combination of hardware, software and/or firmware. When anyof the appended claims are read to cover a purely software and/orfirmware implementation, at least one of the components of the network1300 of FIG. 13 are hereby expressly defined to include a tangiblecomputer readable medium such as computer readable storage medium (e.g.,a memory, DVD, CD, Blu-ray, etc., storing the software and/or firmware).Further still, the network 1300 of FIG. 13 may include one or moreelements, processes and/or devices in addition to, or instead of, thoseillustrated in FIG. 13, and/or may include more than one of any or allof the illustrated elements, processes and devices.

Flowcharts representative of example machine readable instructions forimplementing and/or implementation with the example network of FIG. 13is shown in FIGS. 14. In the examples of FIG. 14, the machine readableinstructions comprise a program for execution by a processor such as theprocessor 408 of FIG. 4. The program may be embodied in software storedon a tangible computer readable medium such as a CD-ROM, a floppy disk,a hard drive, a digital versatile disk (DVD), a Blu-ray disk, or amemory associated with the processor 408, but the entire program and/orparts thereof could alternatively be executed by a device other than theprocessor 408 and/or embodied in firmware or dedicated hardware.Further, although the example programs are described with reference tothe flowcharts illustrated in FIG. 14, many other methods ofimplementing the example network 1300 may alternatively be used. Forexample, the order of execution of the blocks may be changed, and/orsome of the blocks described may be changed, eliminated, or combined.

In certain examples, direct routing optimization can be applied formulticast message traffic as well as unicast traffic. As multicast groupjoin information is forwarded throughout a network (e.g., a LAN), eachzone player or other node in the network (e.g., a household or otherenvironment) becomes aware of each active multicast group and thegroup's membership information. In certain examples, a node uses directrouting optimization to forward multicast traffic as described inconjunction with FIG. 14.

First, a message frame is received (block 1410). For example, a node onthe network, such as the third node 1306 on the network 1300, receives amulticast message including an audio frame and/or timing information forrelay and playback. In certain examples, a type of data (e.g., audiodata, non-audio data, and so on) is examined to determine whethermulticast direct routing should apply. In certain examples, anenvironmental condition (e.g., signal strength, port status, and so on)is examined to determine whether multicast direct routing should apply.

Assuming a node is eligible to consider multicast direct routing, a listof outgoing port(s) to which a multicast frame is to be forwarded isidentified (block 1420). For these outgoing ports, the outgoing portunder consideration should not be in a disabled state. That is, if theoutgoing port is disabled, then wireless communication is not possiblevia that port. Additionally, the outgoing port under consideration isnot the port at which the node received the multicast frame in the firstplace (e.g., outgoing port does not equal incoming port).

The node's ports are evaluated to determine type (block 1430). If atmost “N” of a node's ports are legacy (non-p2p) ports, the node is notgoing to use multicast direct routing optimization. In certain examples,N is set to one (1). For example, if a majority of ports through which amessage frame is to be sent are wired ports, multicast direct routingmay not provide a benefit over the standard or default routing scheme(e.g., a STP-based routing scheme, etc.). However, if a majority ofports (or N less than a threshold, such as N<3) are wireless p2p portsand have an acceptable signal strength (e.g., signal strength for datatransmission greater than a quality threshold), then multicast directrouting is facilitated to the non-legacy ports in the group.

For each outgoing port, the node identifies a list of addresses (e.g.,MAC addresses) that are associated with members of the multicast group(block 1440). The node checks its neighbor table to evaluate whether(e.g., how many) members of the multicast group are its neighbors (orare within a certain threshold number of hops to qualify for directrouting (e.g., 2, 3, and so on)) (block 1450). For example, the nodechecks the neighbor table to determine if at most “M” of the multicastgroup members are not its neighbors. For example, M may be set to one(1).

The node checks the neighbor table to determine if at most “P” of theneighbor nodes have their wired port in a forwarding state (e.g., theport is receiving and sending data in normal operation) (block 1460). Incertain examples, P is set to one (1). Nodes announce the state of theirwired ports through management frames, for example. Thus, in certainexamples, if a majority of nodes are neighbors (or otherwise locatedwithin a certain number of hops) and messages are to be forwarded viawireless p2p ports for a majority of nodes, then multicast directrouting is utilized with respect to those eligible nodes.

If the neighbor table checks are true, the node unicasts the frame toeach “neighbor” node (block 1470). That is, when applying multicastdirect routing optimization, a multicast destination address in eachmulticast frame may be replaced with a unicast destination address foreach target node, for example. Otherwise, the node delivers multicastframes via a default or other “normal” routing protocol (e.g., using aspanning tree) (block 1480).

To prevent expiration of a bridge forwarding entry at a destination nodedue to multicast direct routing, multicast traffic can be periodicallysent using a normal multicast forwarding tree (e.g., according to agoverning STP). In certain examples, a simple network time protocol(SNTP) message transmitted periodically between GM and GC helpsfacilitate updating of a bridge forwarding entry.

The node then awaits a next message to repeat the routing process (block1490).

XI. Conclusion

Thus, certain examples provide systems, methods and apparatus to improvemessage delivery in a network. Certain examples help to facilitateflexible, fast delivery of content on a playback network. Certainexamples accommodate multicast and unicast frame forwarding via wiredand/or wireless port connections.

An example method includes identifying, at a first playback device, amessage including a data frame to be directed to a group of playbackdevices via a network protocol. The example method includes overridingthe network protocol for the group of playback devices to transmit aunicast message via direct routing to each member of the group ofplayback devices that is a neighbor of the first playback device.

Certain examples provide a tangible computer readable storage mediumincluding instructions that, when executed, cause a machine to identifya message including a frame of data to be directed to a group ofplayback devices via a network protocol. The example instructions, whenexecuted, cause the machine to override the network protocol for thegroup of playback devices to transmit a unicast message via directrouting to each member of the group of playback devices that is aneighbor of the first playback device.

Certain examples provide a media playback device including a networkinterface to receive and transmit a data message; a memory to store thedata message; and a processor. The example processor is configured toidentify a message including a frame of data to be directed to a groupof playback devices via a network protocol. The example processor isconfigured to override the network protocol for the group of playbackdevices to transmit a unicast message via direct routing to each memberof the group of playback devices that is a neighbor of the firstplayback device.

The description discloses various example systems, methods, apparatus,and articles of manufacture including, among other components, firmwareand/or software executed on hardware. However, such examples are merelyillustrative and should not be considered as limiting. For example, itis contemplated that any or all of these firmware, hardware, and/orsoftware components can be embodied exclusively in hardware, exclusivelyin software, exclusively in firmware, or in any combination of hardware,software, and/or firmware. Accordingly, while the following describesexample systems, methods, apparatus, and/or articles of manufacture, theexamples provided are not the only way(s) to implement such systems,methods, apparatus, and/or articles of manufacture.

As mentioned above, example methods or processes may be implementedusing coded instructions (e.g., computer readable instructions) storedon a tangible computer readable medium such as a computer readablestorage medium (e.g., hard disk drive, a flash memory, a read-onlymemory (ROM), a compact disk (CD), a digital versatile disk (DVD), acache, a random-access memory (RAM) and/or any other storage media inwhich information is stored for any duration (e.g., for extended timeperiods, permanently, brief instances, for temporarily buffering, and/orfor caching of the information)). As used herein, the term tangiblecomputer readable storage medium is expressly defined to include anytype of computer readable storage medium and to exclude propagatingsignals. Additionally or alternatively, the example processes or methodsmay be implemented using coded instructions (e.g., computer readableinstructions) stored on a non-transitory computer readable storagemedium such as a hard disk drive, a flash memory, a read-only memory, acompact disk, a digital versatile disk, a cache, a random-access memoryand/or any other storage media in which information is stored for anyduration (e.g., for extended time periods, permanently, brief instances,for temporarily buffering, and/or for caching of the information). Asused herein, the term non-transitory computer readable storage medium isexpressly defined to include any type of computer readable medium and toexclude propagating signals.

As used herein, when the phrase “at least” is used as the transitionterm in a preamble of a claim, it is open-ended in the same manner asthe term “comprising” is open ended. Thus, a claim using “at least” asthe transition term in its preamble may include elements in addition tothose expressly recited in the claim.

Additionally, reference herein to “embodiment” means that a particularfeature, structure, or characteristic described in connection with theembodiment can be included in at least one example embodiment of theinvention. The appearances of this phrase in various places in thespecification are not necessarily all referring to the same embodiment,nor are separate or alternative embodiments mutually exclusive of otherembodiments. As such, the embodiments described herein, explicitly andimplicitly understood by one skilled in the art, can be combined withother embodiments.

The specification is presented largely in terms of illustrativeenvironments, systems, procedures, steps, logic blocks, processing, andother symbolic representations that directly or indirectly resemble theoperations of data processing devices coupled to networks. These processdescriptions and representations are typically used by those skilled inthe art to most effectively convey the substance of their work to othersskilled in the art. Numerous specific details are set forth to provide athorough understanding of the present disclosure. However, it isunderstood to those skilled in the art that certain embodiments of thepresent disclosure can be practiced without certain, specific details.In other instances, well known methods, procedures, components, andcircuitry have not been described in detail to avoid unnecessarilyobscuring aspects of the embodiments. Accordingly, the scope of thepresent disclosure is defined by the appended claims rather than theforgoing description of embodiments.

When any of the appended claims are read to cover a purely softwareand/or firmware implementation, at least one of the elements in at leastone example is hereby expressly defined to include a tangible mediumsuch as a memory, DVD, CD, Blu-ray, and so on, storing the softwareand/or firmware.

1-20. (canceled)
 21. A first playback device comprising: a networkinterface; a processor; and a non-transitory computer-readable mediumstoring program instructions that, when executed by the processor, causethe first playback device to perform functions comprising: determiningthat (i) a multicast message including at least one data frame is to betransmitted to a group of playback devices that are communicativelycoupled to the first playback device via a communication network, (ii) adefault network protocol for transmitting messages to the group ofplayback devices blocks direct routing of multicast messages to one ormore second playback devices in the group of playback devices, and (iii)each of one or more third playback devices in the group of playbackdevices is more than one hop in a spanning tree from the first playbackdevice; based on the determining, (i) using the default network protocolto transmit the multicast message to the one or more third playbackdevices over the communication network and (ii) determining to overridethe default network protocol for transmitting messages to the one ormore second playback devices; and after determining to override thedefault network protocol, transmitting a unicast message based on themulticast message to each of the one or more second playback devicesover the communication network.
 22. The first playback device of claim21, wherein determining to override the default network protocolcomprises identifying that a threshold number of outgoing ports of thenetwork interface are of a given type.
 23. The first playback device ofclaim 21, wherein determining to override the default network protocolcomprises identifying that a threshold number of the one or more secondplayback devices is a next hop in the spanning tree from the firstplayback device.
 24. The first playback device of claim 23, whereindetermining to override the default network protocol further comprisesfor any identified one of the one or more second playback devices,evaluating whether the identified playback device has a wired port thatis in a forwarding state.
 25. The first playback device of claim 21,further comprising program instructions stored on the non-transitorycomputer-readable medium that, when executed by the processor, cause thefirst playback device to perform functions comprising: determiningwhether a given playback device in the group of playback devices is aneighbor of the first playback device based on one or more of (i) anetwork distance between the first playback device and the givenplayback device or (ii) a signal strength between the first playbackdevice and the given playback device, wherein the one or more secondplayback devices comprise each playback device of the group of playbackdevices that is determined to be a neighbor.
 26. The first playbackdevice of claim 25, wherein determining whether the given playbackdevice is a neighbor of the first playback device further comprises:determining that the given playback device (i) is a neighbor of thefirst playback device if the signal strength between the first playbackdevice and the given playback device satisfies a threshold conditionrelated to signal strength or (ii) is not a neighbor of the firstplayback device if the signal strength between the first playback deviceand the given playback device does not satisfy the threshold conditionrelated to signal strength.
 27. The first playback device of claim 21,wherein the at least one data frame includes audio data.
 28. A methodcomprising: determining, by a first playback device, that (i) amulticast message including at least one data frame is to be transmittedto a group of playback devices that are communicatively coupled to thefirst playback device via a communication network, (ii) a defaultnetwork protocol for transmitting messages to the group of playbackdevices blocks direct routing of multicast messages to one or moresecond playback devices in the group of playback devices, and (iii) eachof one or more third playback devices in the group of playback devicesis more than one hop in a spanning tree from the first playback device;based on the determining, (i) using, by the first playback device, thedefault network protocol to transmit the multicast message to the one ormore third playback devices over the communication network and (ii)determining, by the first playback device, to override the defaultnetwork protocol for transmitting messages to the one or more secondplayback devices; and after determining to override the default networkprotocol, transmitting, by the first playback device, a unicast messagebased on the multicast message to each of the one or more secondplayback devices over the communication network.
 29. The method of claim28, wherein determining, by the first playback device, to override thedefault network protocol comprises identifying that a threshold numberof outgoing ports of the network interface are of a given type.
 30. Themethod of claim 28, wherein determining, by the first playback device,to override the default network protocol comprises identifying that athreshold number of the one or more second playback devices is a nexthop in the spanning tree from the first playback device.
 31. The methodof claim 30, wherein determining, by the first playback device, tooverride the default network protocol further comprises for anyidentified one of the one or more second playback devices, evaluatingwhether the identified playback device has a wired port that is in aforwarding state.
 32. The method of claim 28, further comprising:determining, by the first playback device, whether a given playbackdevice in the group of playback devices is a neighbor of the firstplayback device based on one or more of (i) a network distance betweenthe first playback device and the given playback device or (ii) a signalstrength between the first playback device and the given playbackdevice, wherein the one or more second playback devices comprise eachplayback device of the group of playback devices that is determined tobe a neighbor.
 33. The method of claim 32, wherein determining, by thefirst playback device, whether the given playback device is a neighborof the first playback device further comprises: determining, by thefirst playback device, that the given playback device (i) is a neighborof the first playback device if the signal strength between the firstplayback device and the given playback device satisfies a thresholdcondition related to signal strength or (ii) is not a neighbor of thefirst playback device if the signal strength between the first playbackdevice and the given playback device does not satisfy the thresholdcondition related to signal strength.
 34. The method of claim 28,wherein the at least one data frame includes audio data.
 35. Anon-transitory computer-readable medium having program instructionsstored on the non-transitory computer-readable medium that, whenexecuted by the processor, cause a first playback device to performfunctions comprising: determining that (i) a multicast message includingat least one data frame is to be transmitted to a group of playbackdevices that are communicatively coupled to the first playback devicevia a communication network, (ii) a default network protocol fortransmitting messages to the group of playback devices blocks directrouting of multicast messages to one or more second playback devices inthe group of playback devices, and (iii) each of one or more thirdplayback devices in the group of playback devices is more than one hopin a spanning tree from the first playback device; based on thedetermining, (i) using the default network protocol to transmit themulticast message to the one or more third playback devices over thecommunication network and (ii) determining to override the defaultnetwork protocol for transmitting messages to the one or more secondplayback devices; and after determining to override the default networkprotocol, transmitting a unicast message based on the multicast messageto each of the one or more second playback devices over thecommunication network.
 36. The non-transitory computer-readable mediumof claim 35, wherein determining to override the default networkprotocol comprises identifying that a threshold number of outgoing portsof the network interface are of a given type.
 37. The non-transitorycomputer-readable medium of claim 35, wherein determining to overridethe default network protocol comprises identifying that a thresholdnumber of the one or more second playback devices is a next hop in thespanning tree from the first playback device.
 38. The non-transitorycomputer-readable medium of claim 37, wherein determining to overridethe default network protocol further comprises for any identified one ofthe one or more second playback devices, evaluating whether theidentified playback device has a wired port that is in a forwardingstate.
 39. The non-transitory computer-readable medium of claim 35,further comprising program instructions stored on the non-transitorycomputer-readable medium that, when executed by the processor, cause thefirst playback device to perform functions comprising: determiningwhether a given playback device in the group of playback devices is aneighbor of the first playback device based on one or more of (i) anetwork distance between the first playback device and the givenplayback device or (ii) a signal strength between the first playbackdevice and the given playback device, wherein the one or more secondplayback devices comprise each playback device of the group of playbackdevices that is determined to be a neighbor.
 40. The non-transitorycomputer-readable medium of claim 39, wherein determining whether thegiven playback device is a neighbor of the first playback device furthercomprises: determining that the given playback device (i) is a neighborof the first playback device if the signal strength between the firstplayback device and the given playback device satisfies a thresholdcondition related to signal strength or (ii) is not a neighbor of thefirst playback device if the signal strength between the first playbackdevice and the given playback device does not satisfy the thresholdcondition related to signal strength.